Reaction product of a diorganic ester of dithiophosphoric acid with a sulfonating agent and the process for making same



Unite States Patent M REACTION PRODUCT OF A DIORGANIC ESTER OF DITHIGPHOSPHGRIC ACID WITHJA SULFO- NATING AGENT AND THE PROCESS-FORMAK- ING SAME William H. Brugmann, Jr.,

Standard Oil Development Company, acorporation of Delaware No Drawing- Application June 29, 1950, Serial No. 171,250

10' Claims. (Cl. 260-461) This invention relates to addition agents for improving the properties of mineral lubricatingoil compositions, and particularly to addition agents which impart relates more detergent and oxidation inhibiting properties to engine lubricants.

It is known that the addition of certain types of metal organic compounds to'lubricating oils improves various properties thereof, such'as theiroiliness characteristics and their detergent action in engines, particularly manifest in the maintenance of a. clean engine during operation; Various metal compounds which have b'eenused for such purposes include the metal derivatives'of such organic compounds as fatty acids, naphthenic acids, petroleum sulfonic acids, alcohols, phenols, and ketones. However, these various metal compounds generally have the disadvantage of tending those of cadmium silverandcopperdead; now so widely used in automotive engines; and' this'is especially true in engines which operate at relatively high: speeds and hightemperatures; It isan object of the present invention to provide a new class of addition agents for oils which are to be used as'crankcaselubricants, in which such agents exhibit the desirable"propertiesof promoting general engine cleanliness, minimizing sludge formation, reducing ring sticking, piston skirt varnish formation, and'the'like, and at the'same'time are comparatively free from a'tendency to cause-corrosion of metal bearings.

The-new class ofadditives which have been found to meet the ab'ove'requirements in ahighly-satisfactory manner'are the" neutral or basic metal salts of the products formed by reacting. adi-organo dithiopliosphoric or di-organo-monothiophosphorous acid witha sulfonating agent; By neutral salt'is -meant a salt formed by re= acting the sulfonated product with just a suflicient amount ofa metallic basic compound to replace all of the'acid reacting hydrogen atoms of the product with a metal; A basic salt is-on'e'containing'more than this amount of metal. The salts may be formed by a neutralization-reaction or by double decomposition of one metal salt with another metal salt. The organic groups of the acid of phosphorus are hydrocarbon groups containing from' 3 to 30 carbon atoms-each, whichmay be alkyl groups, whether saturated or unsaturated, straight chain or branched, or they may be alkary or aralkyl groups containing" at least 2 carbon atoms in a side chain; The sulfonating agent employed may be any sulfonating agent, such'as fuming sulfuric acid, chlorosulfonic acid, fluorosulfonic acid, a sulfur trioxide-dioxane complex in ethyl ether solution, and similar agents. The sulfonation'reaction is exothermic and is accomplished by merely contacting the reagents under controlled temperature conditions, the most suitable temperature having been found to be. of the order of 40 to 15 6., and the best-yields" are generally obtained at temperatures not higher than- C. It is generally preferable to employ'from 1' to 25 mol's' of the sulfonating agent for each mol' of the phosphoruscontaining acid, although on occasion higher 'proporations of the sulfonating agent may be used. An inert solvent is preferably employed. suchas a liquid sulfur dioxide, dioxane, ora saturated liquid aliphatic hydrocarbon, e. g., hexane.

As examples of suitable dithiophosplioric. acids may be mentioned di n-propyl dithiophosphoric acid,- diisobutyl dithiophosphoric acid, di-n h'exyl dithiophosphoric acid, di-n.-octyl dithiophosphoric acid, di-2ethylhexyl di- Elizabetli, N. J., assignor to to corrode all'oy bearings, such as thiophosphoric. acid, di-terteoctyl: ditliiophos giho-ric acid; dilauryl dithiophosphoric acid, diiso'butylphenyl dithioa phosphoric acid, dioleyl dithiophosphoric acid; diethylaphenyl dithiophosphoric. acid, di-tertz-octyl-phenyl:dithio phosphoricacid, di-diamylphenyl dithiophosphoric acid, di-phenylethyl' di'thiopliospho'ric' acid, and similar compounds. Thecorresponding monothiophospliorous. acids are equivalentfor'the'purposes of thepr'e'sent invention. The organo-substituted acids of phosphorus may be readily formedby reacting'an alcohol:- on phenol with a sulfide of phosphorus, e. g., P283, P285, P453, or P487, by methods well known to the art.

Among the alcohols which" are generally preferred for'use as starting materials in the preparation of'th'e monothiophosphorous or dithiophosphoric acids which are sulfonatcd" and converted into metal saltsv in accordance with the present invention may be mentioned ethyl; isopropyl, amyl, Z-ethylhexyl, lauryl, stearyl, and" methyl cyclohexyl alcohols, as well as commercial mixturesof alcohols, such as the mixture ofalcohols essentially'of the. C10 to. C18 range derived from coconut oil and known as Lorol 13 alcohol. Other natural prod ucts containing alcohols such as the. alcohols derived from wool fat, sperm oil, natural waxes and the-like, and alcoholsproduced'by the oxidation of petroleum hydrocarbon products, also the Ox'o alcohols produced from olefins, carbon monoxide and hydrogen, may likewise be' employed! Aromatic compounds such as alkylated phenols. of the typeof. n-butylphenol, tertL-amyI phenol, diamyl. phenol, tert.=octy1. phenol cetyl. phenol; petroleum phenol, and the'like, aswellas thecorresponding naphthols, may be employed. in. like 1 manner;

The metals which are employed forthe neutralization of the sulfonated' product may be any metals, but the alkali and: alkaline earth metals are preferred. Among other metals, magnesium; zinc; beespecially mentioned. The usual" basic metal: com pounds, such as oxides, hydroxides, and: carbonates, may be' employedin! the neutralization reaction;

No formula or other indication of the; exact structure; of the compounds resulting from the above described reactions: is: given; since. from: the: analyses: of the products it has not been: found' possible todetermine whether the sulfonate'gr'oup becomes-zattachedatowone of the organic groupsof: the acidof phosphorus, or whether the sulfhydryl groupof the acid" is converted into a S.SOsH*group. There is also the. possibility that a portion' of the acid may become-:converted into the corresponding: disulfide: compound by'elimination of the hydrogen under. the? oxidizing influence of. the sulfonating; agent.

The amount of the additives of the present inventionwhich are to be employed in mineral lubricating oil: compositions will' normally range; from about 0.02% toabout 5 and the particular: amount in individual cases, will be selected in" accordance with the requirements of the case andin view of. the; properties of thebase. stock employed. Forcommercialrpurposesg.it is convenient to prepare'concentrated oil solutions in which the amount of additive in the. composition rangesafrom.25% to 50% by weight, and to transportand storei'thenrin such form. In preparing a lubricating oil 'composition for use as a crankcase lubricant the additive: concentrate is merely blended with the base'oil' in the required amount.

The'preparation and-testing: of an example: of the additives of the presenteinvention is illustrated in the example described' below, but; it is to be: understood that the additive'prepared and itsuse. in various tests are illustrative only and are not to be: construed as. limiting the scope of the invention in any manner.

Example 1.Preparation of additive 1 molecular proportion (117 g.) of chlorsulfonic acid was addedover aperiod of- /2 hour toan'equal' molecular proportion (354 g.) of di-Z-ethylhexyl dithiophosphoric acid dissolved in 200- cc. of liquid sulfur dioxide, while maintaining'a temperature of 23 to 17 C. The sulfur dioxide solvent was then flashed off, and the product (200 g.) wasblended-with 689- g'rof a solvent extracted Mid-Continent type lubricating oil .stockderived from a- Panhandle crude. and having a viscosity (Say tin, copper: and lead may Phosphorus 1.05% Sulfur 2.42% Barium 2.50% Neutralization No 0.1 alkaline Example 2.--Preparation of additive 1.03 molecular proportions (121 g.) of chlorsulfonic acid was added over a period of 25 minutes to 0.565 molecular proportions (200 g.) of di-Z-ethylhexyl dithiophosphoric acid dissolved in 300 cc. of liquid sulfur dioxide, while maintaining a temperature of 40 to 29 C. The mixture was then stirred for one hour at 37 to 18 C. to insure complete reaction. The sulfur dioxide solvent was then flashed ofi and the product was blended with 800 g. of the same type of lubricating oil solvent that was used in Example 1. This blend was then treated at 80 to 90 C. with 356 g. (1.13 molecular proportions) of Ba(OH)2.8HzO, While bubbling nitrogen through the mixture. An antifoam agent was added and the temperature raised to 150 C. The product was then filtered through Hy-filo. The final product contained about 32% by weight of the barium salt. Analysis of this product gave the following results:

Phosphorus 1.42% Sulfur 2.70% Barium 5.71% Neutralization No 4.75 alkaline Example 3.-Laboratry bearing corrosion test viscosity grade. Samples of these blends and a sample of the unblended base oil were submitted to a laboratory test designed to measure the effectiveness of the additive in inhibiting the corrosiveness of a typical mineral lubricating oil towards the surfaces of copper-lead bearings. The test was conducted as follows:

500 cc. of the oil was placed in a glass oxidation tube (13 inches long and 2% inches in diameter) fitted at the bottom with a inch air inlet tube perforated to facilitate air distribution. The oxidation tube was then immersed in a heating bath so that the oil temperature was maintained at 325 F. during the test. Two quarter sections of automotive bearings of copper-lead alloy of known weight having a total area of sq. cm. were attached to opposite sides of a stainless steel rod which was then immersed in the test oil and rotated at 600 R. P. M., thus providing sufficient agitation of the sample during the test. Air was then blown through the oil at the rate of 2 cu. ft. per hour. At the end of each fourhour period the bearings were removed, washed with naphtha and weighed to determine the amount of loss by corrosion. The bearings were then repolished (to increase the severity of the test), reweighed, and then subjected to the test for additional four-hour periods in like manner. The results are given in the following table as corrosion life, which indicates the number of hours required for the bearings to lose 100 mg. in weight, determined by interpolation of the data obtained in the various periods.

Example 4.-Lauson engine test Blends containing 10% by weight of the concentrate of Example 1 and 6.65% of the concentrate of Example 2 (2% by weight of the active ingredient in each case) in a solvent extracted coastal naphthenic oil of 60 seconds (Saybolt) viscosity at 210 F. and a sample of the unblended base oil were employed as the crankcase lubricants in tests with a Lauson engine operating at 295 F. jacket temperature and 300 F. oil temperature, 1800 R. P. M. speed, and 1.5 indicated kilowatt load, the tests being conducted for 25 hours each. The loss in weight of the copper-lead bearing and the varnish demerit were determined in each case. The varnish demerit rating was based upon a method of rating in which a perfectly clean piston surface had been given a rating of 0 and a demerit rating of 10 was given to the worst condition which could be expected to exist on that surface. The results of these observations are as follows:

; Bearing Varnish WeightLoss Lubricant Demerit (mg/bear- It will be seen from the above data that the additive not only exhibited a detergent effect in lowering the varnish deposits on the piston surface but reduced the amount of corrosion on the bearing to a substantial degree.

The products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates, phosphites, thiophosphates and thiophosphites, guanidine salts, metal xanthates and thioxanthates, metal thiocarbamates, and the like. Other types of additives, such as phenols and phenol sulfides, may also be present.

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from parafiinic, naphthenic, asphaltic or mixed base crudes, or, if desired, various blended oils may be employed as well as residuals, particularly those from which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced by solvent extraction with solvents such as phenol, sulfur dioxide, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils such as polyester or polyglycol type oils, or those prepared, for example, by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. In certain instances cracking coal tar fractions and coal tar or shale oil distillates may also be used. Also, for special applications, animal, vegetable or fish oils or their hydrogenated or volatilized products may be employed in admixtures with mineral oils.

For the best results the base stock chosen should normally be an oil which with the new additive present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory oils, no strict rule can be laid down for the choice of the base stock. The additives are normally sufliciently soluble in the base stock, but in some cases auxiliary solvent agents may be used. The lubricating oils will usually range from about 35 to 150 seconds Saybolt viscosity at 210 F. The viscosity index may range from 0 to or even higher.

Other agents than those which have been mentioned may be present in the oil composition, such as dyes, pour point depressants, heat thickened fatty oils, sulfurized fatty oils, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, rubber, olefin polymers, and the like.

Assisting agents which are particularly desirable as plasticizers and defoamers are the higher alcohols having preferably 8-20 carbon atoms, e. g., octyl alcohol, lauryl alcohol, stearyl alcohol, and the like.

In addition to being employed in crankcase lubricants, the additives of the present invention may also be used in extreme pressure lubricants, engine flushing oils, industrial oils, general machinery oils, process oils, rust preventive compositions and greases.

The lubricating oil compositions disclosed in the foregoing specification are claimed specifically in copending application Serial No. 432,325, filed May 25, 1954, which is a division of the present application.

What is claimed is:

1. As a new composition of matter a non-acidic metal salt of the product formed by reacting one molecular proportion of an acid of phosphorus of the formulawhere R is a hydrocarbon radical containing 3 to 30 carbon atoms and having at least one open chain aliphatic hydrocarbon group containing at least 2 carbon atoms, with from one to two and one-half molecular proportions of iissufonating agent at a temperature of about 40 to 2. A composition according to claim 1 in which the metal of the metal salt is an alkaline earth metal.

3. A composition according to claim 1 in which the metal of the metal salt is barium.

4. A composition according to claim 1 in which R of the formula is an alkyl radical.

5. A composition according to claim -1 in which R of the formula is a 2-ethylhexyl radical.

6. As a new composition of matter the barium salt of the product formed by reacting di-Z-ethylhexyl dithiophosphoric acid with an equal molecular proportion of chlorsulfonic acid at a temperature of -40 to C.

7. The process which comprises reacting one molecular proportion of an acid of phosphorus of the formula where R is a hydrocarbon radical containing 3 to 30 carbon atoms and having at least one open chain aliphatic hydrocarbon group containing at least 2 carbon atoms, with from one to two and one-half molecular proportions of a sulfonating agent at a temperature of about to 15 C., and neutralizing the resulting sulfonated product with a metallic base to form a metal salt of said resulting product.

8. A process according to claim 7 in which the sulfonating agent is chlorsulfonic acid and in which the metglllic base is a basic compound of an alkaline earth met 9. A process according to claim 7 in which the metallic base is barium hydroxide.

10. The process which comprises contacting di-Z-ethylhexyl dithiophosphoric acid with an equal molecular proportion of chlorsulfonic acid at a temperature of 23 to 17 C. in the presence of liquid sulfur dioxide, removing the sulfur dioxide solvent, and treating the resulting sulfonation product with an excess of barium hydroxide at a temperature of -125 C.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,063,629 Salzberg Dec. 8, 1936 2,102,103 Urbain et a1. Dec. 14, 1937 2,417,876 Lewis Mar. 15, 1947 2,465,902 McNab et al Mar. 29, 1949 2,501,731 Mertes Mar. 28, 1950 2,528,257 Vold Oct. 31, 1950 2,560,547 Bartleson July 17, 1951 

1. AS A NEW COMPOSITION OF MATTER A NON-ACIDIC METAL SALT OF THE PRODUCT FORMED BY REACTING ONE MOLECULAR PROPORTION OF AN ACID OF PHOSPHORUS OF THE FORMULA-
 7. THE PROCESS WHICH COMPRISES REACTING ONE MOLECULAR PROPORTION OF AN ACID OF PHOSPHORUS OF THE FORMULA- 